最新刊期
卷 ， 期 9 ， 2006
- 摘要：Two kinids of chitosan derivatives,chitosan condensed with salilylaldehyde and crosslinked chitosan condensed with salilylaldehyde,supported palladium complexes(S-CTS-Pd and CL-S-CTS—Pd)were synthesized and characterized by XPS,TG,DTA etc．TG analysis showed that both S-CTS-Pd and CL-S—CTS-Pd were stable up to 230℃．The complexes were efficient catalysts for Heck arylations of iodoarenes with acrylic acid or styrene under atmospheric condition,and the trails-cinnamic acid or trails—stilbene was obtained in high yield(≥90％)．Neither electron-donating groups nor electron—withdrawing groups on iodoarenes had much effect on the yield of products．The catalytic activities of S-CTS-Pd and CL-S-CTS-Pd decreased slowly while the temperature decreased from 100℃ to 80℃．With reducing reaction temperature continuously,the catalytic activity of S-CTS-Pd reduced remarkably, however．the catalytic activity of CL-S—CTS—Pd remained at a very high level．The influence of amount of catalyst on catalytic performance of S-CTS-Pd and CL-S-CTS-Pd showed that CL-S-CTS-Pd had better performance than S-CTS-Pd．The recyclability of CL-S-CTS-Pd showed that the yield of cinnamic acid was 75．3％ for Heck reaction of acrylic acid with iodobenzene even though the supported catalyst was used 10 times．
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发布时间：2021-03-19 - 摘要：A new and simplistic method,ultrasonic irradiation technique was employed to prepared poly(n—butyl acrylate-co-methyl methacrylate-co-methacrylic acid)[P(BA—MMA—AA)]／TiO2 nanocomposites．By taking advantage of the multiple effect of ultrasound,such as dispersion,pulverization,activation and initiation,the aggregates of TiO2 particles can be broken down．The polymerization of monomers BA,MMA,and functional monomer AA proceeded while TiO2 particles were redispersed by ultrasound．The stable P(BA-MMA-AA)／TiO2 nanocomposite emulsion was obtained．The effects of several main factors,such as surfactant concentration,monomers concentration and the amount of TiO2,on polymerization rate were investigated．The experimental results showed that with increase in SDS surfactant concentration and decrease in monomers concentration and the amount of TiO2 the polymerization rate increased．TEM,SEM and FTIR analyses confirmed that polymers were present on TiO2 surface,and there was strong interaction between TiO2 and polymers with carhoxylic functional groups．DSC,GPC,1H-NMR characterizations showed that with the introduction of TiO2,the average molecular weight of the obtained copolymer decreased, molecular weight distribution became wide．and the BA content of copolymer chains increased compared to that of the pure copelymer,resulting in lower Tg．This method has the following advantages,(1)aqueous medium,(2) without any additional chemical initiator,(3)lower reaction temperature,usually near ambient temperature,(4)ease of operating and(5)the encapsulated polymer layer can be well designed to meet different requirements．
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发布时间：2021-03-19 - 摘要：The biodegradable starch graft copolymer,starch—g—poly(lactic acid)(starch—g-PLA),was directly produced by in situ graft copolymerization of cornstarch with lactic acid using stananus 2-ethyl hexanoate[Sn(Oct)2] as catalyst．The procedure of the grafting reaction was ducidated,based on the HPLC analysis,as the ring-opening polymerization(ROP)from starch surface of the small amounts of lactide produced in situ in the reaction system．Analysis of13C-NMR spectra indicated that ROP of lactide was taken place through acyl—oxygen cleavage co-initiated by hydroxyl group at glucopyranan unit,yielding PLA grafts with a hydroxyl terminus．1H-and13C-NMR spectra were employed to assign the characteristics resonances of the copolymer．The positions of lactyl units at the glucopyranan ring as well as the corresponding distribution are determined．The DS values of the graft copolymer calculated based on13C-NMR spectra of starch ring carbons are indentical to those of carbonyl carbons in LA moieties．The reactivity of hydroxyl groups at glucopyranan rings decreases in the order of C-6>C-3>C-2．while the average length of PLA grafts increases in the order of C-3
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发布时间：2021-03-19 - 摘要：Nanofibrous poly(vinylidene fluoride)membranes were produced by the electrespinning method．Since these electrospun membranes have microporous structure,they can be applied as polymer electrolyte for lithium ion battery．The morphology of electrospun membranes was strongly affected by the concentration of polymer solutions.It presents a usual web of fibers at a concentration of 15 wt％,a web of fibers with a few beads at a lower concentration (10 wt％)and a cross-linked web of fibers at a higher concentration(18 wt％)The electrospun PVDF membranes show a high uptake of liquid electrolyte and good compatibility with metal lithium．The electrospun PVDF-based electrolyte membranes exhibited the maxima of uptake(340％)and ion conductivity(1．57×10-3S·cm-1)at room temperature．At a 0．5 mA·am-2rate,the coin cell with the electrospun PVDF-based polymer electrolyte had good cycling performance with little capacity fade after 50 cycles at 25℃．Even at 60℃,the coin cells show a good stability．
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发布时间：2021-03-19 - 摘要：Three types of novel impact modifiers were prepared by melt blending maleic anhyaride—grafted ethylene-octene copelymer(POE-g-MAH)with polypmpylene(PP)through a twin screw extruder．The effect of different impact modifier and its content on mechanical properties,dispersion morphology and melting and crystallization behavior of the blends was investigated．The mechanical property testing indicates that POE—g—MAH and PP have significantly synergistic toughening effect on PBT．The impact modifier(POEg2)with POE—g-MAH／PP ratio of 70／30 has the best toughening effect．When POEg2 content is up to 15％,the notched impact strength(Ig)increases from 7．5 kJ／m2 for pure PBT to 51．2 kJ／m2,which is approximately equal to that for the blend toughened by 15％ pure POE-g-MAH,and the loss of tensile strength(σb)of the blend is the least．The impact modifier particles dispersed in matrix have a soft shell—rigid core morphology evidenced by using AFM and SEM．DSC results reveal that the soft shell in shell-core structurat particles becomes incomplete,when the PP content in the impact modifier is high(50％)．It may which result in a decline in interaction between the blend components,and consequently,Is and σb of the blend both begin to decrease obviously．
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发布时间：2021-03-19 - 摘要：Iron tetracaboxyphthalocyanine(Fe-CPc)and cobalt tetracaboxyphthalocyanine(Co—CPc)were synthesized and characterized by element analysis and FT-IR．The products were supported by modified cellulose fibers in acidic condition to obtain a novel deodorizing fibers．The results show that FePcF(fibers—supposed Fe—CPc),CoPcF(fibers-supported Co—CPc)and CoFePcF(fibers-supported Fe-CPc and Co—CPc)can remove methanthiol,hydrogen sulfide,ammonia and trimethylamine effectively at room temperature．Methanthiol and hydrogen sulfide were removed by the mechanism of catalytic oxidation,while ammonia and trimethylamine by the mechanism of neutralization．The efficiency of these fibes in deodorizing methanthiol and hydrogen sulfide has the following order CoFePcF>CoPcF>FePcF．
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发布时间：2021-03-19 - 摘要：Dispersion copolymerization of acrylamide(AM)and N,N—dimethylaminoethyl methacrylate methyl chloride quatemary salt(DMC)has been carried out in aqueous solution of ammonium sulfate in the presence of poly(acryloylxyethyltrimethyl ammonium chloride)(PDAC)as polymeric stabilizer using 2,2'-azobis[2-(2-inidazolin．2-yl)propane]-dihydro chloride(VA-044)as the initiator．The results showed that varying the stabilizer concentration in a range from 6 wt％to 14 wt％,a minimum of average particle size was obtained at the stabilizer concentration of 10 wt％．When fixing stabilizer concentration as a constant,the average particle size decreased with increasing the average molecular weight of stabilizer．Ammonium sulfate has great effect on the dispersion polymerization,and only in a narrow range of concentrations of the inorganic salt and the monomer,particles with smooth edge(good morphology)can be obtained．The molecular weight of the polymer obtained decreases with increasing the ammonium sulfate concentration．
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发布时间：2021-03-19 - 摘要：A gene of a membrane protein,Arehaerhedopsin-4(AR4),was expressed into anH．salinarum strain L133,which is negative for synthesis of bacterio-opsin and whose lipid environment is free of carotenoid．The carotenoid has three characterized absorption peaks at 480,508 and 544 nm which cover the absorption peak of membrane protein AR4 at 5700 nm at the ground state．In contrast to the wide-type AR4 isolated from the conventional strain H．sp．xz515,the recombinant AR4 removed the binded carotenoid．The underlying photochromic properties of the recombinant AR4 was thus improved,and the contrast between M410 intermediate and ground state was greatly enhanced．Composite films were further made by embedding the recombinant AR4 into pely(vinyl alcohd)(PVA)．By enhancing its pH,the decay of the M intermediate Was slowed down．A simple pattern recording as an optical information storage material was also realized by the compostie films．During this process,Iight was illuminated into the composite covered with a mask,and the pattern in the mask was observed even after removing the mask．Hence．this paper demonstrates that the polymer technique and gene engineering could be combined tO prepare information materials with both the biological activities of proteins and the good processing properties of polymers．
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发布时间：2021-03-19 - 摘要：Suffonated polyetheretherketone(SPEEK)with various degree of sulfonation(DS)was prepared by sulfonation of commercial VictrexR PEEK．The DS was determined using 1H-NMR method．A series of composite membranes based on SPEEK and phosphotungstic acid(PWA)were prepared by solution casting method．The effects of the DS and PWA content on water uptake,swelling ratio,proton conductivity and methanol permeability of the composite membranes were investigated．The proton conductivifies of the composite membranes inereased with the DS and the PWA content and reacbed a highest value of 1．36×10-2S／cm(20℃),which was higher that that of the NafionR117 membrane(1．0×10-2S／cm)measured under the same condition．Nearly one order magnitude difference between conductivities measured in transverse and longitudinal directions was found．Thorugh the methanol permeability increased upon the addition of PWA．the methanol permeability of the composite membranes was all lower than that of the Nafion R 117 membrane．
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发布时间：2021-03-19 - 摘要：Polyaniline containing benzo-12-crown-4 small cycle crown ether functional groups in side chains was synthesized．It was used to prepare a mixed electron-ion conductor by complexing with lithium salt and doping with dodecyl benzene sulphonic acid(DBSA)．The conductivity of the mixed conductor was tested,using the four-probe method．and its value is as high as 10-2S／cm at room temperature．The designed chemical structure of product was proved by means of the FT-IR analysis．The surface morpholog of samples was studied by scanning electron microscopy．X—ray diffraction analysis demonstrated that this kind of mixed conduetor is an amorphous solid,which is favorable for ionic conductivity．TG shows that the thermal stability of the synthesized polymer is very good．
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发布时间：2021-03-19 - 摘要：Poly(1,5-diaminonaphthalene)(1,5-DAN)films were prepared by cyclic voltammetry on an indium tin oxide(ITO)plate working electrode in acetonitrile and acid aqueous solutions,respectively,and were characterized with FT—IR．The electroactivity of polymer films was examined by changing the polymeric solvents,film thickness and doping acid．A highly electroactive polymer film was obtained in acid aqueous solutions．With increasing the potential scan rate,however,the loss of amount of charge is more in an acid oqueous solution than that in acetonitrile．The results showed that the film thickness did not increase linearly with increasing the amount of charge used during polymerization．The UV-Vis spectra were collected while petentiostatic technique was performed under various applied voltage．and the electronic band gap was testified from the onset of the π-π* transition of the neutral pelymer．
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发布时间：2021-03-19 - 摘要：The preparation and microwave—absorbing behavior of polyaniline—DBSA／montmori]lonite(PANI-DBSA／ MMT)nanocomposites were studied．The nanccomposite was synthesized by emulsion polymerization using dodecylbenzensulfonic acid(DBSA)as dopant and emulsifier．XRD,FT-IR and conductance measurements of the nanocomposite showed that the conductive emeraldine salt form of polyaniline was inserted into the layers of MMT to produce the nanocomposites with high conduetivity．The complex permittivity and permeability of a 2．00 mm thick specimen containing 50％ by weight of PANI—DBSA／MMT nanocomposite and PANI—DBSA were measured respectively in the range of 2～18 GHz,from which the reflection loss(RL)of microwaves was calculated and comparative absorption curves were given．The results shows that the PANI—DBSA／MMT nanocomposite is capable of absorbing 2．0—18 GHz microwaves,and the reflection loss is greater than -10 dB within the frequency range of 9．1—12．5 GHz．while the maximum reflection loss was-15．8 dB at 11 GHz．
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发布时间：2021-03-19 - 摘要：Crystal morphology,internal structure of dispersed phase and phase morphology for two impact polypropylene copolymers with the same ethylene content,rubber content,relative molecular weight and relative molecular weight distribution,but obviously different toughness were investigated by polarized optical microscope,differential scanning calorimetry,wide angle X—ray diffraction,dynamic mechanical analysis and atomic force microscope．It was found that the crystallization morphology and behavior of both samples were simile,but the compatibility between the dispersed phase and the matrix in IPC-A was better than that in IPC-B．Moreover,phase composition of the matrix and the dispersed phase of the different IPC were analyzed．It was found that the dispese phase displayed a complex concealment structure．Models of phase structure were proposed to describe the phase structure of both IPC heterophase systems and the action of E-b-P in the IPC．It is suggested that phase morphology phys a more important role as a compatibilizer in enhancing impact strength of IPC．
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发布时间：2021-03-19
Research Article
- 摘要：Three hyperbranehed poly(siloxysilanes)were prepared from AB3-type monomers at the presence of Karstedt catalyst．The detailed synthesis procedures of AB3-type monomers by reaction between γ-methacryloyloxy propyltrimethoxysilane or vinyltrimethoxysilane with chlorosilane using anhydrous ferric chloride as the catalyst were described．This new approach can simplify the synthetic routes for hyperbranched polysiloxanes．FTIR,1H-NMR,13C-NMR,29Si—NMR,elemental analysis and SEC／MALLS were employed to identify the structure of the polymers．The analyses revealed that the reaction between alkoxysilane and chlomsilane could be feasibly catalyzed by anhydrous ferric chloride．The reaction of vinyltrimethoxysilane with chlorsilane could be carried out more easily than that of γ—methylacrycyloxypropyltimethoxylsilane with chlorosilane due to its steric hindrance effect．
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发布时间：2021-03-19 - 摘要：A kind of novel biodegradable triblock copolymers of poly(γ-benzyl L-glutamate)-b-poly (tetrahydrofuran)-b-poly(γ-benzyl L-glutamate)was synthesized by using amino-terminated poly(tetrahydrofuran) as a macroinitiator to initiate the anionic ring-opening polymerization of γ-benzyl L-glutamate N—carboxyanhydride (BLG-NCA)made from the reaction of γ—benzyl L-glutamate with triphosgen in tetrahydrofuran．The molecular structure was characterized by IR,1H-NMR,DSC and GPC measurements．The results showed that the triblock copolymers are well tailored by varying the feeding molar ratio of monomer to macroinitiator below 100．DSC analysis indicated that no crystalline phase is found in the copolymers and the glass transition temperature of each block gets close gradually with the block length of poly(γ-benzyl L-glutamate)growing．These triblock polymers could act as potential candidates for drug delivery carriers and tissue—engineered scaffolds．
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发布时间：2021-03-19 - 摘要：A six-member cyclic carbonate with protected functional groups was synthesized from tetramethylolmethane,benzaldehyde and ethyl choroformate．Coplymerization of D,L-lactide with cyclic carbonate was carried out throush conventional ring-opening polymerization using Sn(Oct)2 as the catalyst．The effects of different catalysts,polymerization time and monomer-to-catalyst molar ratio on the molecular weight were investigated．The methods of removing protected groups were studied．Results showed the protected groups were effectively removed via catalytic hydrogenation．Poly(D,L-lactide-co—cycliccarbonate)s with hydroxyl pendant functional groups was obtained．
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发布时间：2021-03-19 - 摘要：The melts of a series of low molecular weight poly(ethylene oxide)(PEO)fractions on mica surfaces were studied by atomic force microscopy(AFM)and X-ray reflectivity(XRR)measurement．The PEO ultrathin films were obtained via static dilute solution casting．Different from the melts of the PEO with both methoxyl-(—OCH3)end groups that are dewetted on the mica surface,a pseudo-dewetting phenomenon of the PEO melts was observed when either one end group of the PEOs becomes hydroxyl(—OH)or both are hydroxyl groups．The wetting layer thicknesses of the pseudo—dewetted melts were measured to be 4．5～4．7 nm,independent on the molecular weight and the end groups of PEOs．However,the PEO melt droplets on the wetting layer varied from spherical caps with relatively high contact angle to irregular shapes with relatively low contact angle when increasing the molecular weight and the hydrophobicity of end groups of PEOs．
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发布时间：2021-03-19
Research Bulletin
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